xfs: close the RT and log block devices in xfs_free_buftarg

Closing the block devices logically belongs into xfs_free_buftarg,  So
instead of open coding it in the caller move it there and add a check
for the s_bdev so that the main device isn't close as that's done by the
VFS helper.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: "Darrick J. Wong" <djwong@kernel.org>
Message-Id: <20230809220545.1308228-6-hch@lst.de>
Signed-off-by: Christian Brauner <brauner@kernel.org>

fs/xfs/xfs_buf.c

@@ -1938,6 +1938,8 @@ void
 xfs_free_buftarg(
 	struct xfs_buftarg	*btp)
 {
+	struct block_device	*bdev = btp->bt_bdev;
+
 	unregister_shrinker(&btp->bt_shrinker);
 	ASSERT(percpu_counter_sum(&btp->bt_io_count) == 0);
 	percpu_counter_destroy(&btp->bt_io_count);
@@ -1946,6 +1948,9 @@ xfs_free_buftarg(
 	blkdev_issue_flush(btp->bt_bdev);
 	invalidate_bdev(btp->bt_bdev);
 	fs_put_dax(btp->bt_daxdev, btp->bt_mount);
+	/* the main block device is closed by kill_block_super */
+	if (bdev != btp->bt_mount->m_super->s_bdev)
+		blkdev_put(bdev, btp->bt_mount);
 
 	kmem_free(btp);
 }